Forget Mars—let’s go colonize Titan!

Humans don't deserve to colonize another planet unless they can survive on Earth for another 100,000 years. Otherwise you're just proposing to migrate our current limitations to an even more restrictive environment. Extra-Earth "colonization" in this century is absurd.

"Deserve"? What does that even mean? 100,000 years? We could have a catastrophic meteor strike in that time easily, and that might be it, the whole shebang. Or a lot else could go wrong. You want to potentially doom the all known life (sentient or not, even) over some unquantifiable existential dare?

I think, if we don't fail here on earth first, we will go to all these places.

I'm pretty sure we're going to fail on Earth and all this discussion is pretty pointless. We're not going anywhere unless we clean up our problems on Earth. And we won't.

We will not have enough resources for meaningful space exploration unless nations of the Earth unite. And that isn't going to happen.

It's pretty obvious to me that humanity is failing.

The Earth will have enough resources for space exploration for at least the next several hundred years. Unless you are talking about human resources and short of a nuclear war I think we'll have those too. Warming and rising sea levels isn't going to be good by any measure, but it won't be the end of the world. Unless nukes of course.

Venus has a surface temperature of ~450 C. Better atmospheric and magnetospheric shielding from radiation than Mars or the moon, but I think the temperature (and atmospheric chemical) conditions would make it a longer gamble than Mars for colonization. You couldn't walk around on Venus for long with any environment suit we have designed. We haven't even gotten close to the lander probe successes we've had with Mars on Venus because its temperatures cook everything.

Trying to send humans to the surface of Venus is insane. Establishing a colony in an aerostat about 50km above the surface is significantly more plausible, but you would need to develop the ability to launch rockets from an aerial platform if you ever wanted to bring anyone home.

Balloon launched rockets have been done before, but it's generally not cost effective on Earth because on Earth, the ground is a convenient place to launch from, and the propellant cost of getting to orbit is more about going fast than going high, so starting higher doesn't buy you much. On Venus, launching from higher up in the atmosphere would be more of a necessity, but we could develop and test the technology needed in Earth's atmosphere if we wanted to.

At 50km up, the temperature, pressure, and radiation protection is comparable to Earth. There's high wind speed, but if the colony is moving with the wind, you would need to worry more about turbulence than absolute wind speed, so it might not be a problem. You would need to wear something to protect you from the acidic environment, and you would need an oxygen mask, but at that altitude, Venus would be one of the most hospitable environments in the solar system for a human (aside from Earth, obviously).

I think Venus would be more challenging than Mars, but it's not really the surface conditions of Venus that we should be concerned about, since that's almost certainly not where we would be building a colony.

Venus has a surface temperature of ~450 C. Better atmospheric and magnetospheric shielding from radiation than Mars or the moon, but I think the temperature (and atmospheric chemical) conditions would make it a longer gamble than Mars for colonization. You couldn't walk around on Venus for long with any environment suit we have designed. We haven't even gotten close to the lander probe successes we've had with Mars on Venus because its temperatures cook everything.

Trying to send humans to the surface of Venus is insane. Establishing a colony in an aerostat about 50km above the surface is significantly more plausible, but you would need to develop the ability to launch rockets from an aerial platform if you ever wanted to bring anyone home.

Balloon launched rockets have been done before, but it's generally not cost effective on Earth because on Earth, the ground is a convenient place to launch from, and the propellant cost of getting to orbit is more about going fast than going high, so starting higher doesn't buy you much. On Venus, launching from higher up in the atmosphere would be more of a necessity, but we could develop and test the technology needed in Earth's atmosphere if we wanted to.

At 50km up, the temperature, pressure, and radiation protection is comparable to Earth. There's high wind speed, but if the colony is moving with the wind, you would need to worry more about turbulence than absolute wind speed, so it might not be a problem. You would need to wear something to protect you from the acidic environment, and you would need an oxygen mask, but at that altitude, Venus would be one of the most hospitable environments in the solar system for a human (aside from Earth, obviously).

I think Venus would be more challenging than Mars, but it's not really the surface conditions of Venus that we should be concerned about, since that's almost certainly not where we would be building a colony.

As a near-term research station sure. But as a colony, wouldn't it be extremely hazardous to try to extract anything from the local environment in order to be self-sustaining beyond free gases? I mean it would be difficult on mars and the moon too but it seems at least less imminently deadly.

Venus has a surface temperature of ~450 C. Better atmospheric and magnetospheric shielding from radiation than Mars or the moon, but I think the temperature (and atmospheric chemical) conditions would make it a longer gamble than Mars for colonization. You couldn't walk around on Venus for long with any environment suit we have designed. We haven't even gotten close to the lander probe successes we've had with Mars on Venus because its temperatures cook everything.

Trying to send humans to the surface of Venus is insane. Establishing a colony in an aerostat about 50km above the surface is significantly more plausible, but you would need to develop the ability to launch rockets from an aerial platform if you ever wanted to bring anyone home.

Balloon launched rockets have been done before, but it's generally not cost effective on Earth because on Earth, the ground is a convenient place to launch from, and the propellant cost of getting to orbit is more about going fast than going high, so starting higher doesn't buy you much. On Venus, launching from higher up in the atmosphere would be more of a necessity, but we could develop and test the technology needed in Earth's atmosphere if we wanted to.

At 50km up, the temperature, pressure, and radiation protection is comparable to Earth. There's high wind speed, but if the colony is moving with the wind, you would need to worry more about turbulence than absolute wind speed, so it might not be a problem. You would need to wear something to protect you from the acidic environment, and you would need an oxygen mask, but at that altitude, Venus would be one of the most hospitable environments in the solar system for a human (aside from Earth, obviously).

I think Venus would be more challenging than Mars, but it's not really the surface conditions of Venus that we should be concerned about, since that's almost certainly not where we would be building a colony.

As a near-term research station sure. But as a colony, wouldn't it be extremely hazardous to try to extract anything from the local environment in order to be self-sustaining beyond free gases? I mean it would be difficult on mars and the moon too but it seems at least less imminently deadly.

I think any colony on Venus would need to depend on the atmosphere for most of their needs. The surface of Venus is very inhospitable even for robotic probes, but the density of the atmosphere means that if they could develop some kind of surface mining drone that could gather resources, they could probably lift a pretty heavy payload back to the colony using a balloon (assuming that they could make a drone and balloon that could survive on the surface long enough to be useful).

The logistics might get pretty complicated if the drone could only survive on the surface for a limited time, but needed to rendezvous with a colony that was drifting on a layer of atmosphere moving very fast relative to the surface of the planet.

Lemme edit that... Tens of thousands of years is orders of magnitude beyond the horizon of prediction. Arguably just 100 years is already sketchy in terms of reliable predictions, in IT/AI, manufacturing, energy, biology, and probably more. Because of the accelerating pace of developments, multiplied by unknown unknowns in each, multiplied by their mutual influences.

Many things deemed weird 50 or 100 or 500 (never mind 10k) years ago are ho hum today. Likewise today for the same jumps forward. For instance, curing aging is one fundamental that once accepted will make our time seem barbaric (because self imposed lack of choice of when to die, for the sake of dubious traditional status quo) and despite seeming totally out past left field, it actually is as deeply humane as the need to expand off Earth into astronomically better industrial base/living space/etc of asteroids/planets/beyond and actually addresses the last of the three fundamental aspects of scarcity: matter, space, time.

And thus such a seemingly pie in the sky piece thing is actually central piece of the puzzle. It solves the whole problem of travel time with STL travel. And shifts the entire picture of what it means to be human, when you have long enough to see the other developments needed to get past everything holding back people from that universal pursuit of happiness, to at least doubling the few decades of whatever they deem their happiness, specifically enabled by more technological progress within that extra lifespan.

To keep it to technological aspect, without opening the can of worms of sociopolitical status quo's way past their due date that something like curing aging, or ubiquitous energy, fast fabrication of *nearly* everything, maybe not full AI but definitely more than the last 50 years brought us, etc, that definitely will happen within something like "10,000 years".

I think tunnels are far more feasible. That or shielding that is filled with water-ice or some other liquid that would freeze (we're going to need to find a lot on Mars or the Moon anyhow for a colony). Let's remember that less gravity means we can make structures that would be impossible on Earth. That means huge tunnels or surface structures are quite feasible. And if we have inflatable structures that are filled with water that turns to ice, that should be relatively cheap and provide a good shield (and protection from breaches).

Again though, tunnels are pretty feasible too. Naturally we'd want to send robots ahead of time to construct the tunnels. Personally I'd rather have us figure the robot construction of a habitat out first, do that, then send people.

For Venus, I don't think that's pretty risky without a lot more work and experimentation on floating habitats. If it sinks then everyone dies, which means you need a ton of testing. Mars and the Moon are much easier and closer to our current construction experience. I think Venus would be a great potential terraforming target, but we're talking on the order of hundreds of years for that.

Another option is large space stations in Lagrange points. I think that has a lot to offer and is also more feasable and reachable than Titan -- let's not forget the food cost of going to Titan -- it would be insane. Titan and the Outer Solar System are something where it makes more sense to work on AFTER we have a lot of infrastructure to support it and are very used to long trips in space.

Haven't red the book but from here the proposal seems a bit... weird. cause anyway you look at it, Titan is one of the least hospitable places in the solar system.

One leak and you, or the installation, are torched. Batteries failing and you 're icicle. No solar power. You can't pressurize the habitats cause the atmospheric pressure on Titan is higher than Earth's. The amount of gear neded to take a walk almost equals to a space suit. Too far away. Nobody's sure about the properties of the "solid" land. The "seas" are so cold you 'd need tailored material to sail, explore or harvest. No water, at least near the surface.

The more you think about it, the more weird a proposal you find it. For a fraction of the cost and tech risk, you could have a real Moon base. And when it comes to habitability, even Mars is way better. There's the radiation problem, but a few inches of dirt on top of a habitat is enough to protect the explorers/colonists. The atmosphere is thin but that can change gradually. The temperature is all right, especially inside the huge ground depressions. Mars is far closer.

I really don't get it. I 'd dismiss it right away if it didn't come from the particular people, so I quess I 'll have to read the book before going on with the rant.

Forget Titan. Let's colonize, expand Las Vegas, Detroit and other places in the US where air, water, infrastructure already exist. Oh, wait, not possible due to scarcity of water etc.Propulsion is to space travel as buggy whips are to the Indianapolis 500.

I can't help but think that any contemporary ideology that could rally world governments and educated, exceptional people into this kind of endeavor -going big instead of starting small- would most likely be seen post-hoc as a reprehensible thing that only ended up eating up massive resources to send people into suicide exploratory missions, considering all the things that can and will most surely would go wrong. In the end having a long-term chilling effect into space exploration.

Maybe the book will change my mind, i'll give it a look.

I don't disagree. I am very worried that we'll eventually end up with a small moon colony that just eats $ and loses support when taxes have to go up 0.5% to pay for it. I don't think a off world settlement would be self sustaining economically for decades if not centuries. I am all for doing what it takes to leave Earth but am super concerned about public support to do so.

Mercury might be the most economical colonization site, depending on the mineral deposits. If there are accessible deposits of precious metals, it has a low cost to transport there, acceptable but not too strong gravity, and water ice and acceptable temperatures at the north polar area. Metals can be shipped back to Earth/low earth orbit via solar-powered railgun. While I doubt that anyone would want to stay there too long, it would certainly make money.

With an oxygen mask and enough warm clothing, humans could roam Titan's surface in the dim sunlight.

"enough warm clothing" is a sealed environmental suit with heavy duty heating and lots of insulation. We're talking about an environment where liquid ethane and methane are common, you're not roaming the surface in an oxygen mask and a parka.

Similarly, you're most likely going to be living in tunnels indistinguishable from those used on Mars. You're not going to have big glass domes or Earth-style surface cities, again because of the cryogenic environment. Mars may actually be much better for surface structures, with the right arrangements of shielding.

Not only is it a very cold atmosphere, but it's also a dense atmosphere, so it should be really good at pulling heat away from poorly protected meatbags. On the plus side, if you need to keep your data center cool on Titan, you could just duct some outside air past your heat sinks.

Temperatures on Mars can also get very cold, but I'm guessing that the thin atmosphere of Mars would be less effective at sucking away body heat. There's a reason we use a layer of near vacuum as insulation when we want to keep our drinks hot or cold in a thermos.

Even worse than the dense atmosphere are the liquids I mentioned. Not only are they even denser than the atmosphere, human-friendly temperatures are well above their boiling points, so any fraction that warms on contact with you will boil away with what's left remaining at cryogenic temperatures. Get something soaked with methane, and it isn't warming above ~111 K until it dries.

Not only is this a problem for us, it'll have a similar effect on hardware as a dip in liquid nitrogen. That's certainly no insurmountable obstacle, we'll just be limited to materials that can handle cryogenic temperatures, but it helps make it clear just how absurd the "oxygen mask and warm clothes" claim was.

I can't help but think that any contemporary ideology that could rally world governments and educated, exceptional people into this kind of endeavor -going big instead of starting small- would most likely be seen post-hoc as a reprehensible thing that only ended up eating up massive resources to send people into suicide exploratory missions, considering all the things that can and will most surely would go wrong. In the end having a long-term chilling effect into space exploration.

Maybe the book will change my mind, i'll give it a look.

I don't disagree. I am very worried that we'll eventually end up with a small moon colony that just eats $ and loses support when taxes have to go up 0.5% to pay for it. I don't think a off world settlement would be self sustaining economically for decades if not centuries. I am all for doing what it takes to leave Earth but am super concerned about public support to do so.

Mercury might be the most economical colonization site, depending on the mineral deposits. If there are accessible deposits of precious metals, it has a low cost to transport there, acceptable but not too strong gravity, and water ice and acceptable temperatures at the north polar area. Metals can be shipped back to Earth/low earth orbit via solar-powered railgun. While I doubt that anyone would want to stay there too long, it would certainly make money.

Mercury is much closer to the Sun's gravity well and it is also really hot near there. So that means a lot more energy needed to get out and you have to be a very careful about heat or everyone dies. Also, any colony on Mercury would probably have to be constantly moving to stay on the dark side. Though I suppose you could make something in geo-synchronous orbit.

It makes more sense to try to get materials from the asteroid belt really.

The first few colonies we have will most likely be government-funded or done for research purposes or done as part of a very long-term investment. If anything there's going to be a race between that and not needing colonies because robots will do everything for less (which is going to become true for most jobs over the next several decades most likely).

I think, if we don't fail here on earth first, we will go to all these places.

I'm pretty sure we're going to fail on Earth and all this discussion is pretty pointless. We're not going anywhere unless we clean up our problems on Earth. And we won't.

We will not have enough resources for meaningful space exploration unless nations of the Earth unite. And that isn't going to happen.

It's pretty obvious to me that humanity is failing.

The Earth will have enough resources for space exploration for at least the next several hundred years. Unless you are talking about human resources and short of a nuclear war I think we'll have those too. Warming and rising sea levels isn't going to be good by any measure, but it won't be the end of the world. Unless nukes of course.

You know, you don't need the "end of the world" for civilization to collapse to the point where flinging stuff into space is no longer a possibility. A few wars, throw in a side of famine with a heaping helping of mass migration and not too many governments or corporations are going to be interested in launching rockets.

So it is about an unlikely target specifically based on an unlikely technology motivated by an unlikely reason? [Not that some of now dwindling again spike in wars was not partly motivated by AGW driven local drought. But the long term trend has been going down for the better part of a century, not up.] And dismissing that colonizers may work for their future generations rather than a vacation paradise of their own?

I think, if we don't fail here on earth first, we will go to all these places.

I'm pretty sure we're going to fail on Earth and all this discussion is pretty pointless. We're not going anywhere unless we clean up our problems on Earth. And we won't.

We will not have enough resources for meaningful space exploration unless nations of the Earth unite. And that isn't going to happen.

It's pretty obvious to me that humanity is failing.

The Earth will have enough resources for space exploration for at least the next several hundred years. Unless you are talking about human resources and short of a nuclear war I think we'll have those too. Warming and rising sea levels isn't going to be good by any measure, but it won't be the end of the world. Unless nukes of course.

You know, you don't need the "end of the world" for civilization to collapse to the point where flinging stuff into space is no longer a possibility. A few wars, throw in a side of famine with a heaping helping of mass migration and not too many governments or corporations are going to be interested in launching rockets.

Also, Earth's reserves of mineral and energy resources are far from exhausted, but all the easily accessible ones are long gone. A collapse of civilization may leave us unable to rebuild to the point where we can manage spaceflight. That means no weather satellites, resulting in a substantial reduction in agricultural efficiency and ability to deal with extreme weather events, no communications satellites, no GPS...not to mention monitoring of environmental damage by a civilization that has lost its high-tech industrial base or as a consequence of whatever caused the collapse in the first place.

Even if we can only establish enough off-planet presence to put up simplified replacement comms, GPS, and weather satellites, that could be enough to greatly decrease the death toll and speed the recovery of civilization back on Earth. A redundant off-planet industrial base capable of producing moderately sophisticated electronics could also be a major boost in rebuilding: processors and memory would easily be worth importing for an Earth that has lost its ability to fabricate its own.

We don't need to make Earth less hospitable than Mars for extending our civilization off-planet to be of great value.

We don't need to make Earth less hospitable than Mars for extending our civilization off-planet to be of great value.

assumes facts not in evidence. You're willing to cast off millennia of evolution and assume we can just go "colonize" another planet or moon which has no breathable atmosphere, no easily obtained water, markedly different gravity, and be just fine and dandy?

We've evolved to live on the surface of this planet. Colonizing the Moon, Mars, Titan, or whatever is nothing more than the fever dreams of some geeks who watched too many sci-fi TV shows when they were kids.

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Also, Earth's reserves of mineral and energy resources are far from exhausted, but all the easily accessible ones are long gone.

So the best thing to do is extract what's left and fire it off into space, never to be usable here again. Like Maher said in the linked video, NASA estimates it'll take $450 billion just to get to a single manned mission to Mars. And we know NASA always comes in within budget. If we're going to spend that much to try to overhaul a planet, shouldn't we do this one?

When discussing Mars, many people ignore the facts about heat. The temperature of Mars is low at night, but the thin atmosphere does not do a good job of stealing heat from habitats. With aerogel insulation of maybe 50 cm thickness, a human body can generate enough heat to warm a modest living pod.

This concept comes from rather simple calculations and may be off a bit due to complexities not considered. Also, it in no way obviates the other problems of Mars. Radiation is a problem because even low radiation can ever so slowly destroy our very fragile brains. Living underground or in buried habitats will be required. I suggest one architecture in my articles on living on Mars that might work well enough to avoid the cave syndrome, but that would require a bit more heat energy.

We can get to Mars. Traveling to Titan is a stretch at best and probably won't happen for decades at least. If we can live in the ISS, we can live on Mars, which has more resources and a slightly higher atmospheric pressure.

Every problem with respect to living on Mars can be solved by existing (some yet to be fully developed) technologies -- except for these three.

1. Gravity. No one knows what the impact of 0.38g will be on humans in the long term. Who knows? It could be positive, or it could be devastating.

2. Psychology. Can humans really survive the loneliness, the lack of life outside of the habitat, the ennui of a planet whose surface hasn't changed in any significant way in over a billion years? We don't know, but we do know that it won't be easy.

3. Return on investment. Scientific research can take us only so far. The huge investment required to establish a self-sustaining colony on Mars is far beyond that required merely to land there and return. The only potential I see is as a waystation for asteroid mining and how that works is unclear.

We can do Mars. Just going there with humans will be a gigantic accomplishment. It will be exciting. However, then what?

I assume we'll eventually address (this century) the propulsion equation - at least enough to reduce trip time to Saturn down to months, rather than years.

The real problem that Titan has is gravity. It's even a shade under that on the Moon. Mars, with its 0.38G gravity, might or might not have serious physiological effects on humans, but whatever those effects are, they'll be worse on Titan. And there's no easy fixing that.

But by the time we can reach Titan easily, we'll undoubtedly have significant experience of human habitation on both the Moon and Mars, so I expect we'll know just how bad the equation will be there.

I think you'd get poisoned pretty fast on Titan. We better have cancer in check before going there, then probably fine.

We should be in space. Screw planets. When you need gravity for exercise and bone loss, spin a habitat, but be out of the damned gravity well.

Largescale spun habitats really are, for now, the only way we really have to *completely* (well, nearly so) replicate Earth conditions in space. Including gravity, which is not something we can artificially adjust on the Moon, Mars, or Titan.

Problem is, we are not yet in a position to economically construct such habitats. We might be, perhaps, by century's end, on a limited scale.

Venus has a surface temperature of ~450 C. Better atmospheric and magnetospheric shielding from radiation than Mars or the moon, but I think the temperature (and atmospheric chemical) conditions would make it a longer gamble than Mars for colonization. You couldn't walk around on Venus for long with any environment suit we have designed. We haven't even gotten close to the lander probe successes we've had with Mars on Venus because its temperatures cook everything.

There was a great deal of discussion previously in the comment thread on what a feasible Venusian colony would look like, so I didn't feel I needed to include a ton of explanation in my comment. There has also been a great deal of discussion since, but I've learned my lesson.

The pressure and temperature 50km above the surface of Venus is the closest to Earth in our solar system. The air we breathe is thinner than Venus at that altitude, and would, therefore, provide lift. There's no need for complicated pressurization of the habitats, nor is there any risk of explosive decompression. There's also no need for pressurized suits, just sealed protective suits and breathing apparatus.

Gravity is also more ideal. The gravity on Venus is 0.904g, compared to 0.38g for Mars. If that causes any issues with bone or muscle deterioration, it would be more gradual than on Mars. The record time spent in microgravity was 438 days, and we don't know what years on Mars will do to human physiology. We also don't know if we can even reproduce, or raise the next generation in that environment. Because of its proximity, the moon presents a better location to study the long-term effects of microgravity on the human body and reproduction. Cloud colonies on Venus are unlikely to have an issue with bone/muscle deterioration, reproduction, or rearing.

Launch windows for Venus occur every 584 days (1.6 years), compared to the 780 days (2.14 years) for Mars. It takes less time/energy to reach Venus. Entry, descent, and landing (albeit not so much landing in this case) would be easier on Venus than Mars. It's possible to aerocapture large payloads. You descend with parachutes, and simply deploy balloons at the right altitude. Gliders and airplanes are possible on Venus.

Solar intensity on Venus, above the clouds, is 2x that of Earth, much less Mars. Even down in the cloud layer, solar intensity is comparable to Earth, depending on the wavelength. Venus' atmosphere also offers protection from radiation and meteorites.

Everything necessary for survival can be obtained from the atmosphere. As to the feasibility of expanding the colony, there are proposals for mining drones that can be used to retrieve materials from the surface. The pressure on the surface is 93 bar, which is equivalent to an ocean depth of 1km. The temperature is 462° C. We can handle that, and we have materials that are resistant to sulfuric acid.

We haven't had lander probe successes on Venus because we've sent fuck all there. NASA had one atmospheric multiprobe mission 40 years ago, which wasn't designed to reach the surface (though one did). The Russians had a lot more Venus missions, but nothing they sent was designed to survive long term. The balloons they launched survived until their batteries ran out. Everything since then, spanning 33 years since 1984, has been an orbit or flyby. No atmospheric probes, no balloons, and no landers. We have nothing planned right now, with DAVINCI being rejected last year. The Russians' Venera-D is proposed for 2021-2025.

Forget Titan. Let's colonize, expand Las Vegas, Detroit and other places in the US where air, water, infrastructure already exist. Oh, wait, not possible due to scarcity of water etc.Propulsion is to space travel as buggy whips are to the Indianapolis 500.

Las Vegas is problematic, but Detroit does have these gigantic fresh water bodies called Lake Huron and Lake Erie nearby.

Forget Titan. Let's colonize, expand Las Vegas, Detroit and other places in the US where air, water, infrastructure already exist. Oh, wait, not possible due to scarcity of water etc.Propulsion is to space travel as buggy whips are to the Indianapolis 500.

Las Vegas is problematic, but Detroit does have these gigantic fresh water bodies called Lake Huron and Lake Erie nearby.

Don't forget Lake St. Clair and the Detroit River (actually a strait between St. Clair and Erie that lent the city its name - strait in French is "détroit").

Back on topic...

"The radiation and lack of gravity that make long-range space travel a risk would all bite anyone we sent to explore Mars. NASA assumes it'll find solutions, but the authors are critical of the Agency promoting a journey to Mars without already having solved them."

Aren't these actually pretty much solved? If you really can't stand to have people in zero-g for 6 months on the way to Mars, then put the hab on the end of a tether with a counterweight (expended upper stage, supply module or similar) and impart some spin. The huge rotating torus like in the The Martian would also work, though at much greater expense.

As for radiation, make sure you have a shielded room/core in the hab module in case of emergencies and otherwise just deal with it. What's the lifetime increase to cancer risk of 6 months in space? I'm not sure exactly, but I bet there'd be people who would go to Mars even if you told them they were certain to get cancer later in life because of it.... much less simply increasing their odds of cancer.

Humans don't deserve to colonize another planet unless they can survive on Earth for another 100,000 years. Otherwise you're just proposing to migrate our current limitations to an even more restrictive environment. Extra-Earth "colonization" in this century is absurd.

"Deserve"? What does that even mean? 100,000 years? We could have a catastrophic meteor strike in that time easily, and that might be it, the whole shebang. Or a lot else could go wrong. You want to potentially doom the all known life (sentient or not, even) over some unquantifiable existential dare?

There's been a fair few mass extinctions and big asteroids already and none of them took out all life so I doubt yet another asteroid will do it.

As for a lot else going wrong I'm guessing you mean some type of political flare up? If so that's kind of a catch 22, we'll need the ability to cheaply travel to other planets if we want to colonise. After that, for it to be better for off world to rebuild Earthly things rather than the people of Earth rebuilding on their own after catastrophe space travel would have to be cheaper again. If space flight gets that cheap and easy then the problems of Earth are the problems of off world colonies.

I don't agree with any humans don't "deserve" to do this type talk, but asteroid scaremongering doesn't sway me and they're kind of right if the argument is about global thermonuclear war or the like.

As Einstein would say, this is a great thought experiment, but lets look at a few harsh realities. With current technology it would take almost seven years for a spacecraft to get to Titian. It would take a massive logistics effort to sustain a minimal crew for that length of time. The supplies needed would be huge, that drives up the amount of energy to boost that material. That requires more fuel which would again drive up the energy requirement. It's a vicious circle. Then the issue of communication, at the speed of light, it takes over an hour to get a signal to Titian, and of course the return signal, so any real time communication is impractical if there was any issue that was beyond the capabilities of the crew. Then the environment of Titian is not as balmy as the article states. It would take more than "warm clothes and an oxygen mask" to be on the surface of Titian. I would love to see a manned mission to Titian, but we need to develop the infrastructure and technology to make it more than a one way suicide mission.

Venus has a surface temperature of ~450 C. Better atmospheric and magnetospheric shielding from radiation than Mars or the moon, but I think the temperature (and atmospheric chemical) conditions would make it a longer gamble than Mars for colonization. You couldn't walk around on Venus for long with any environment suit we have designed. We haven't even gotten close to the lander probe successes we've had with Mars on Venus because its temperatures cook everything.

Trying to send humans to the surface of Venus is insane. Establishing a colony in an aerostat about 50km above the surface is significantly more plausible, but you would need to develop the ability to launch rockets from an aerial platform if you ever wanted to bring anyone home.

Balloon launched rockets have been done before, but it's generally not cost effective on Earth because on Earth, the ground is a convenient place to launch from, and the propellant cost of getting to orbit is more about going fast than going high, so starting higher doesn't buy you much. On Venus, launching from higher up in the atmosphere would be more of a necessity, but we could develop and test the technology needed in Earth's atmosphere if we wanted to.

At 50km up, the temperature, pressure, and radiation protection is comparable to Earth. There's high wind speed, but if the colony is moving with the wind, you would need to worry more about turbulence than absolute wind speed, so it might not be a problem. You would need to wear something to protect you from the acidic environment, and you would need an oxygen mask, but at that altitude, Venus would be one of the most hospitable environments in the solar system for a human (aside from Earth, obviously).

I think Venus would be more challenging than Mars, but it's not really the surface conditions of Venus that we should be concerned about, since that's almost certainly not where we would be building a colony.

As a near-term research station sure. But as a colony, wouldn't it be extremely hazardous to try to extract anything from the local environment in order to be self-sustaining beyond free gases? I mean it would be difficult on mars and the moon too but it seems at least less imminently deadly.

I think any colony on Venus would need to depend on the atmosphere for most of their needs. The surface of Venus is very inhospitable even for robotic probes, but the density of the atmosphere means that if they could develop some kind of surface mining drone that could gather resources, they could probably lift a pretty heavy payload back to the colony using a balloon (assuming that they could make a drone and balloon that could survive on the surface long enough to be useful).

The logistics might get pretty complicated if the drone could only survive on the surface for a limited time, but needed to rendezvous with a colony that was drifting on a layer of atmosphere moving very fast relative to the surface of the planet.

The good part about Venus is that you can use balloons to descend to the surface, mine materials, and then rise back up. The bad part is that the balloons must be rather robust. Who said space would be easy?

After Mars, the next major Solar System bodies on which a manned landing might be made would be Mercury and Pluto. Or asteroids, or planetary satellites such as Titan. Venus and the gas giants are obviously out.

While it would take a truly catastrophic event to make Earth less habitable than anywhere else in the Solar System, a base elsewhere might be secure from a thermonuclear war, or a global dictatorship, thus serving to preserve our culture, our technology, and so on.

I doubt even a full-scale nuclear war or runaway global warming would reduce the carrying capacity of the Earth to that of Mars or anywhere else in this system.

Try thinking along the lines of nanotechnology gone awry and a grey-goo scenario. Or disease genetically designed to eliminate humans. Stuff that isn't possible today, but which might be in, say, 50 years. There are religious fanatics who would actively welcome the end of days. There are military fanatics who genuinely believed in Mutually Assured Destruction; that is, a retaliation that would also destroy their enemy even if their own destruction was already unavoidable. We could mess this planet up real good. Well beyond any natural disaster.

Don't forget Lake St. Clair and the Detroit River (actually a strait between St. Clair and Erie that lent the city its name - strait in French is "détroit").

Lake St. Clair is a frickin' duck pond. (/me lives near the lake.) Just go up M-29/M25 around the edge of the thumb. Lake St. Clair is greenish-brown depending on how shallow and muddy, but once you get past the Blue Water Bridge Lake Huron is a beautiful aqua blue.

Also a pipe dream. IIRC all "biodome" type experiments on Earth have failed miserably and that was with a rescue crew living next door. What hope there is for establishing a long term colony in space? Even the Sahara desert is a paradise teeming with life in comparison.

We should focus first on fixing Earth, there is no end of hard and very interesting challenges here. A space related one is building a planetary defense against asteroids, the most inmediate existential threat against humanity.

Venus has a surface temperature of ~450 C. Better atmospheric and magnetospheric shielding from radiation than Mars or the moon, but I think the temperature (and atmospheric chemical) conditions would make it a longer gamble than Mars for colonization. You couldn't walk around on Venus for long with any environment suit we have designed. We haven't even gotten close to the lander probe successes we've had with Mars on Venus because its temperatures cook everything.

There was a great deal of discussion previously in the comment thread on what a feasible Venusian colony would look like, so I didn't feel I needed to include a ton of explanation in my comment. There has also been a great deal of discussion since, but I've learned my lesson.

The pressure and temperature 50km above the surface of Venus is the closest to Earth in our solar system. The air we breathe is thinner than Venus at that altitude, and would, therefore, provide lift. There's no need for complicated pressurization of the habitats, nor is there any risk of explosive decompression. There's also no need for pressurized suits, just sealed protective suits and breathing apparatus.

Gravity is also more ideal. The gravity on Venus is 0.904g, compared to 0.38g for Mars. If that causes any issues with bone or muscle deterioration, it would be more gradual than on Mars. The record time spent in microgravity was 438 days, and we don't know what years on Mars will do to human physiology. We also don't know if we can even reproduce, or raise the next generation in that environment. Because of its proximity, the moon presents a better location to study the long-term effects of microgravity on the human body and reproduction. Cloud colonies on Venus are unlikely to have an issue with bone/muscle deterioration, reproduction, or rearing.

Launch windows for Venus occur every 584 days (1.6 years), compared to the 780 days (2.14 years) for Mars. It takes less time/energy to reach Venus. Entry, descent, and landing (albeit not so much landing in this case) would be easier on Venus than Mars. It's possible to aerocapture large payloads. You descend with parachutes, and simply deploy balloons at the right altitude. Gliders and airplanes are possible on Venus.

Solar intensity on Venus, above the clouds, is 2x that of Earth, much less Mars. Even down in the cloud layer, solar intensity is comparable to Earth, depending on the wavelength. Venus' atmosphere also offers protection from radiation and meteorites.

Everything necessary for survival can be obtained from the atmosphere. As to the feasibility of expanding the colony, there are proposals for mining drones that can be used to retrieve materials from the surface. The pressure on the surface is 93 bar, which is equivalent to an ocean depth of 1km. The temperature is 462° C. We can handle that, and we have materials that are resistant to sulfuric acid.

We haven't had lander probe successes on Venus because we've sent fuck all there. NASA had one atmospheric multiprobe mission 40 years ago, which wasn't designed to reach the surface (though one did). The Russians had a lot more Venus missions, but nothing they sent was designed to survive long term. The balloons they launched survived until their batteries ran out. Everything since then, spanning 33 years since 1984, has been an orbit or flyby. No atmospheric probes, no balloons, and no landers. We have nothing planned right now, with DAVINCI being rejected last year. The Russians' Venera-D is proposed for 2021-2025.

ANYTHING you try and suspend in the atmosphere will fail and end up on the surface eventually and that eventually will occur much sooner than ideal. Unrecoverable catastrophe is a near given in this scenario.

Pretty hard sci fi until the very end when it gets highly speculative.

That's to be expected when a story has "fi" in its genre name.

Not sure if you're just messing with me or not, but I'll bite. There are gradations of scifi. Hard would be generally adherent to real world science with minimal (or even sometimes just one) element of divergence, and that can have a varying degree of speculation as well. On the other end of the scale the softest scifi is basically fantasy with science mumbojumbo trappings. I phrased it the way I did because the author (who is a mathematician and engineer) did a very good job of making it plausible given what we knew at the time. Without giving too much away though, the last chapter leaps forward in time and becomes completely speculative which is inconsistent with the rest of the book... thus my caveat.

It was written playfully, I'm glad you assumed that.

I appreciate your distinction in the various flavors and gradations of sci-fi. I respect that others like it but my least favorite is probably sci-fi/fantasy. Though I do read pure fantasy so I suppose I have some hypocrisy there.

We're talking about books but on a side note when it comes to film I can't stand that until recently almost every movie labeled sci-fi was actually horror/sci-fi.

Anyway, having read Titan I get that reaction to the last part. My take on hard sci-fi is a little different but I agree it felt inconsistent. At the same time I think Baxter felt he needed an epilogue that was slightly less of a downer and the only way to really do that in context was jump ahead slightly.

My own take on hard sci-fi is that I've felt too much of it didn't speculate enough. I get incredibly frustrated with authors that denigrate ideas like warp travel or dimensional shifting as "hand waving" or "magic". Are those ideas speculative? Yes, but only in the context of our technological limitations considering the ideas have solid grounding in actual science. Even if you can get such authors and many of their followers to acknowledge the real math that's been brought to bear on these concepts they'll still wave it away (condescendingly of course) as being hundreds of years away. I have yet to gain an insight as to what they're basing these assumptions on other than hubris and arrogance.

Ooh, that was a rant. Sorry.

Uh, I probably could have just said yes, it was written with a grin and yes, I agree the last part of "Titan" was inconsistent with the rest of the book.

*if you're a fan of hard sci-fi I recommend Catherine Asaro's first novel "Primary Inversion". It's not often we get women in hard sci-fi and this was just an incredible introduction to her talent.

Venus has a surface temperature of ~450 C. Better atmospheric and magnetospheric shielding from radiation than Mars or the moon, but I think the temperature (and atmospheric chemical) conditions would make it a longer gamble than Mars for colonization. You couldn't walk around on Venus for long with any environment suit we have designed. We haven't even gotten close to the lander probe successes we've had with Mars on Venus because its temperatures cook everything.

There was a great deal of discussion previously in the comment thread on what a feasible Venusian colony would look like, so I didn't feel I needed to include a ton of explanation in my comment. There has also been a great deal of discussion since, but I've learned my lesson.

The pressure and temperature 50km above the surface of Venus is the closest to Earth in our solar system. The air we breathe is thinner than Venus at that altitude, and would, therefore, provide lift. There's no need for complicated pressurization of the habitats, nor is there any risk of explosive decompression. There's also no need for pressurized suits, just sealed protective suits and breathing apparatus.

Gravity is also more ideal. The gravity on Venus is 0.904g, compared to 0.38g for Mars. If that causes any issues with bone or muscle deterioration, it would be more gradual than on Mars. The record time spent in microgravity was 438 days, and we don't know what years on Mars will do to human physiology. We also don't know if we can even reproduce, or raise the next generation in that environment. Because of its proximity, the moon presents a better location to study the long-term effects of microgravity on the human body and reproduction. Cloud colonies on Venus are unlikely to have an issue with bone/muscle deterioration, reproduction, or rearing.

Launch windows for Venus occur every 584 days (1.6 years), compared to the 780 days (2.14 years) for Mars. It takes less time/energy to reach Venus. Entry, descent, and landing (albeit not so much landing in this case) would be easier on Venus than Mars. It's possible to aerocapture large payloads. You descend with parachutes, and simply deploy balloons at the right altitude. Gliders and airplanes are possible on Venus.

Solar intensity on Venus, above the clouds, is 2x that of Earth, much less Mars. Even down in the cloud layer, solar intensity is comparable to Earth, depending on the wavelength. Venus' atmosphere also offers protection from radiation and meteorites.

Everything necessary for survival can be obtained from the atmosphere. As to the feasibility of expanding the colony, there are proposals for mining drones that can be used to retrieve materials from the surface. The pressure on the surface is 93 bar, which is equivalent to an ocean depth of 1km. The temperature is 462° C. We can handle that, and we have materials that are resistant to sulfuric acid.

We haven't had lander probe successes on Venus because we've sent fuck all there. NASA had one atmospheric multiprobe mission 40 years ago, which wasn't designed to reach the surface (though one did). The Russians had a lot more Venus missions, but nothing they sent was designed to survive long term. The balloons they launched survived until their batteries ran out. Everything since then, spanning 33 years since 1984, has been an orbit or flyby. No atmospheric probes, no balloons, and no landers. We have nothing planned right now, with DAVINCI being rejected last year. The Russians' Venera-D is proposed for 2021-2025.

ANYTHING you try and suspend in the atmosphere will fail and end up on the surface eventually and that eventually will occur much sooner than ideal. Unrecoverable catastrophe is a near given in this scenario.

What are you basing that on? Maintenance will be required, as with any offworld colony not perfectly earthlike.